Antenna structure



SePt- 21, 1937 w. M. HAHNEMANN 2,093,886

ANTENNA STRUCTURE Original Filed Aug. 13, 1932` 5 Sheets-Sheet 1 il H WT q-M--mgiA-u am"- 2/wwam Wa//er Man/Hahnemann @Hwy sept 21, 1937. w. M. HAHNEMANN 2,093,886

ANTENNA STRUCTURE Original Filed Aug. l5, 1932 5 Sheets-Sheet 2 .fm/*miur Wa//er Max Ha/Mmmm SePt- 21, 1937- W. M. HAHNEMANN 2,093,886

ANTENNA STRUCTURE 5- Sheets-Sheet 5 Original Filed Aug. i5, 1932.

Sept' 21, 1937- W. M. HAHNEMANN 2,093,886

ANTENNA STRUCTURE Original Filed Aug. 13, 1932 5 Sheets-Sheet 4 Sept 21, 1937. w. M, HAHNEMANN i `.2,093,886

ANTENNA STRUCTURE Original Filed Aug. 13, 1952 5 Sheets-Sheet 5 Patented seni. 21, 1937 i Zasn ANTENNA STRUCTURE Walter Max Hahnemann, Berlin-Marienfelde,

Germany, assigner to C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a com- Daily Original application August 13, 1932, Serial No. 628,674. Divided and this application .lnly 27, 1935, Serial No. 33,467. In Germany October 7, 1931 5 Claims. (Cl. Z50- 33) This application is a divisional from the cocenter of oscillation is somewhat more than M4 pending application Serial No. 628,674, filed Aufrom the ground. gust 13, 1932, for Antenna structures, and is in- With such a distance a very sharp ground raditended for use with broadcast transmitters. ation occurs in the case of a single dipole without In order to avoid local fading phenomena in harmful space radiations arising. E designates 5 broadcast transmitters, i. e. to remove the field the transmission line from which the dipole is fed of fading as far as possible from the transmitter, over a coupling device K. antenna combinations have been suggested which The action of such a dipole antenna is eX- produce the least possible space radiation and plained hereafter with reference to the diagrams l radiate as much energy as possible in the form of shown in Figs. 4 and 5. It will especially be statl0 direct or ground radiation. Fading phenomena ed of what kind is the influence due to the dis'- then only occur in an area in which the ground tance between the center of oscillation and the ray has lower intensity than the reflected space earth. By earth is alWaYS meant the .electriray, i. e. at a substantial distance from the transcally active earth layer. l mitter. To such end it has been proposed to eX- The radiation diagram may be CalCUllatedin l5 tend aso-called Marconi antenna, i. e. a grounded the Well known manner by TesOlVing the TaClia" aerial structure operating at about M4, vertically tion into radiation due t0 the dipole itself and upward to such an extent that if possible it has radiation from an image 0f the dipole in the a height of M2. i denotes the operative waveearth. The image is shown in dotted lines in length. Fig. 2. If the distance between the centers of os- 20 Such arrangements operating at M2 have not CillatiOn 0f the OliDOle Di (Fig- 2) and the image had the desired result. This is obviously due to diDOle is CliOSen a little greater than M2, Which the fact that at the lower end of the antenna, corresponds t0 a distance somewhat greater than f that is to say in the vicinity of the ground, dis- M4 above earth. then the ground radiation is a turbing elds occur, which may be designated as maXimllm While lhei'e is n0y disturb-ing Space 25 reversa] ie1d5- These disturbing fields Cause an radiation. By increasing that distance still more oblique upward radiation which does not enable the gfOilnCl TadiatOn iS further increasing. but local fading to be Overcome in a, Satisfying secondary maxima then occur which entail a dismanner, turbing space radiation and thus will impair the In accordance with the invention the antenna reception in the vicinity 0f the transmitter. 30 consists of a vertical dipole whose center of oscil- When this distance is fedi-leed a TadiatiOn dan y iation is Somewhat more than a, quarter of a gram is obtained which corresponds more to the wavelength above the earths surface so that a WellkHOWn Maieeni I'adiatiOn diagram. radiation diagram results in which the ground Fig. shows d1p0les arranged all? pfogl'esslvely 35 radiation is predominating The distance of the lncreaslng distances from the earth. Here again center o-f oscillation from the ground is so chosen the distance relatimships are explained by means that the secondary maxima, if any, are below a of the images of the dipoles. In Fig. 4 the ralimt adapted to impair the reception. The mag diation diagrams for the distances M3 to 0375A are illustrated.

nitude of the secondar maxima de ends u on 40 the operative Wavelengt p p In Fig. 4 the Marconi curve 1s designated M. 40

In the accompanying drawings Fig l shows The values M3 to.0.75\, indicated in Fig. 4, show the occurrence of disturbing elds in the vicinity to which of. the dlples Illustrated m Fig' @Sich of the ground radlation diagram, 1. e. each of the curves lnside Some embodiments of the invention are shown the Curve M relate' It Wm be Seen that the 45 distance M3 gives a radiation diagram which is substantially flatter than the Marconi curve M ments. Figs. 3, 4 and 5 are diagrams relating to $515241? gcgggemgtones Weggg the mode of action 0f the novel arrangement ever be seen from the curve thatwith a value Figs. 6, 7, 8, 8a and 9 are elevations of still other bei-,Ween M2 and 2,/3 the Secondary maxima are `50 embOCllmentsstill so small that disturbances in the vicinity of In the Slmplest Case, Wlllell 1S sllOWn in Flg 2. the transmitter, i. e. local fading phenomena,

a Vertical antenna Di, Vibrating as a diDOle. is are not likely to occur. The secondary maxima arranged over the electrically conducting layer are shown on the left in Fig. 4.

50 of earth, preferably at such a height, that the The decrease of local fading also depends upon in Figs. 2 to 9 of the accompanying drawings.

Fig. 2 is an elevation of one of these embodithe wavelengths employed. In accordance with the wavelength the formation of the secondary maxima will be diierent. 'Therefore in Fig. 5 the field intensity curves of the space and ground radiations are shown for the diiierent cases to which Figs. 3 and 4 relate. From the points of intersection of the field intensity curves it can be inferred from what distances fading phe-V nomena are to be expected. It will be seen that the conditions depend upon the wavelengths employed. Hence it follows that .the fading phenomena occur as soon as the space ra-diation happens to be in preponderance ofthe ground radiation. Therefore, in determining the distance between the center of oscillation and the earth it should be considered that this question also depends upon the distance within which the reception is to be free of fading. Ii for instance a wavelength of 260 meters is used, then with a distance of say 2/3 disturbances result already ata distance of about km. from the transmitter, since at this place the curve for 2/3A intersects the curve of the ground wave of 260 meters. If however a wavelength of 390 meters is employed the curves only intersect at a distance of km. from the transmitter.

In order correctly to keep to these relationships also in practice, an earth must be employed which is best adapted for the purpose and is of a constant character. To such end earth structures may be used which are composed of several small earths. The diameter of the earth structure should however be as great as possible and at least M2.

The dipoles need not be M2, but in order to save mast height, may be chosen substantially smaller and tuned by additional means of elongation. In order not to impair the radiation eiiiciency too much, however, unless special steps are taken, the reduction of the length must be kept Within certain limits. In order to increase the efficiency it is therefore adapted for the purpose to arrange at the ends of the dipole short horizontal conductors which aid in the current distribution to the oscillating members.

The energization of the dipole can be effected either by current coupling, for instance by conveying the energy to them at the center' by field action, or potential couplings can be used which permit energization at the ends of the antenna. Such kinds of energization are shown in Figs. 6 and '7.

Fig. 6 shows an arrangement with the least possible mast height. Between two masts M an antenna is suspended which consists of a hori- Zontal member N and a member O` suspended perpendicular thereto. The energization .takes place at the oscillatory center through current coupling and at a height greater than M4 above the earth. The antenna N, O is tuned as a dipole vibrating at M2. They masts M need only be slightly higher than the distance of the center of oscillation from the ,earths surface, so that for the relatively long waves of the broadcasting range mast heights are obtained which do not exceed the height of the ordinary antennae.

In the device according to Fig. 7 two masts Mcarry a dipole consisting of two horizontal members N, N and a vertical member O connected therewith.A The transmission line E is coupled over a lead F with the dipole. This lead has two parallel wires f, g. The wire f is conductively connected with the dipole. The wire g ends free. The dipole has a potential loop at the point where wire f is connected to the member N. The connection of the lead F to this point is therefore called a potential coupling. This is the so-called Zeppelin energization, the operation of which is based on the fact that the currents in f are co-phasal to the currents in g, so that the feeder F does not radiate, radiation being restricted to the dipole N. ON'. It may also be arranged that cophasal currents Y which may be formed are cancelled in their effect. Coupling coils which are closely coupled together and are wound in appropriate directions may serve this purpose.

In the structure shown in Fig. 8 the dipole Di is so suspended on the mast M that the center of oscillation of the dipole is more than M4 above the earth. In order to save mast height the length of the dipole is reduced with respect to M2. To provide forlthe proper operation of the dipole there are arranged at its ends conducting members L which are as far as possible or approximately horizontally arranged.r These meme bers are guyed from the mast M to an auxiliary mast H by ropes S. The auxiliary mast H can be dispensed with if the upper rope S is anchored to the ground and the lower rope guyed to it, as shown in Fig. 8a. The feeding of the dipole takes place by a transmission line E which is erected in the mast M and coupled to the dipole by a coil K.

In the device according to Fig. 9 the mast M has cross members Ti, T2 between which are arranged dipoles Di. These are xed to the cross pieces TI, T2 by conducting members L which also act as bracing wires. The dipoles for example may be arranged in fours around the mast M and are jointly energized from the transmission line E over the coupling line K. As shown in the drawings the dipoles are spaced from the mast a distance small compared to the wave-length at which the dipoles are adapted to operate, this arrangement resulting in a reduction of the iield to which the mast is subjected during operation of the antenna structure.

By the arrangement according to Fig. 9 a ground radiation is obtained which is of the same intensity on all sides.

What is claimed is:

1. An antenna structure comprising a plurality of vertically disposed dipoles arranged about and supported by a mast with the centers Iof oscillation of said dipoles positioned more than a quarter wavelength above the earths surface but sufciently close thereto to produce substantial ground radiation and means for jointly energizing said dipoles.

2. An antenna structure comprising a plurality of vertically disposed dipoles arranged in fours about and supported by a mast with the centers of oscillation of said dipoles positioned more than a quarter wavelength above the earths surface but suilciently close thereto to produce substantial ground radiation and means for jointly energizing said dipoles.

3. An antenna structure comprising a plurality of vertically disposed dipoles disposed around and supported by a mast, coupling means in each of said dipoles, and a feed line coupled to said dipoles by said coupling means, said dipoles being spaced from said mast a distance small compared to the wavelength at which said dipoles are adapted to operate.

4. An antenna structure comprising a pair of vertically disposed dipoles positioned at opposite sides of a supporting mast and spaced therefrom a distance small compared to the Wavelength at which said dipoles are adapted to operate, coupling means in each of said dipoles and a feed line coupled to said dipoles by said coupling means.

5. An antenna structure comprising a mast, a plurality of vertically disposed dipoles arranged in fours around said mast and spaced therefrom a distance small compared to the Wavelength at which said dipoles are adapted to operate, coupling means in each of said dipoles and a feed line coupled to said dipoles by said coupling me ans WALTER. MAX HAHN EMANN 

